Wireless communications access, on which our society and economy is growing increasingly dependent, is becoming pervasive in all aspects of daily societal functions. For example, wireless communication has become increasingly available to users on board mobile platforms such as land vehicles, aircraft, spacecraft, watercraft or the like. Wireless communication services for passengers of mobile platforms include Internet access, e.g., e-mail and web browsing, live television, voice services, virtual private network access and other interactive and real time services.
Wireless communication platforms for remote, hard to access, or mobile user terminals, e.g., mobile platforms, often use communication satellites that can provide service coverage over large geographic footprints, often including remote land-based or water-based regions. Generally, base stations, e.g., a ground base station, send information (e.g., data) to the user terminals through a bent pipe via one or more satellites. More specifically, the base stations send information on a forward link to the satellite that receives, amplifies and re-transmits the information to an antenna of one or more fixed or mobile user terminals. The user terminals, in turn, can send data back to the base stations via the satellite. The base stations can provide the user terminals with links to the Internet, public switched telephone networks, and/or other public or private networks, servers and services.
Modern satellites and other cellular communication systems often employ a number of spot beams providing a beam laydown that forms coverage over a geographic region that may be divided into a plurality of cells. In a communication system using spot beams, the same frequency may be used at the same time in two or more cells. These beams may be configured to maintain a predetermined co-polar isolation (e.g., carrier-to-interference ratio) value in order to minimize the interference among beams. This is called spatial isolation and spatial reuse. In one typical parlance, each spot beam may be assigned a color to create a color pattern that matches a frequency reuse pattern. Identical frequencies, then, may be reused by different beams with the same color.
These cellular communication systems often face a number of challenges in optimizing services for a variety of types of user terminals, while staying within system constraints. The systems often require high system capacity to provide simultaneous voice and data. Links providing voice services are often noise dominate and require high satellite antenna gain, whereas those providing data services often require optimization of opposing satellite-antenna criteria. That is, data links are often interference dominant and require high side-lobe suppression to provide a high signal-to-interference ratio.
Many modern cellular communication systems are often configured to permit communication by a variety of types of user terminals in the coverage region, which may benefit from different, sometimes-opposing satellite-antenna criteria for optimal performance. The different types of terminals may also benefit from different frequency reuse patterns and/or cell sizes. Small-sized handheld terminals often benefit from higher satellite antenna gain to close links with the satellite, and may also benefit from a medium-to-high-order frequency reuse with mid-sized cells. Mid-sized portable and vehicular terminals on the other hand often benefit from higher side-lobe suppression to provide a correspondingly higher signal-to-interference ratio, as well as a higher-order frequency reuse to provide higher-rate data services to a higher-density user base with micro-sized cells. And large-sized aeronautical and maritime terminals often benefit from a lower-order frequency reuse to provide data services to a lower-density user base with large-sized cells. And aeronautical terminals in particular often travel at high speeds, and may benefit from larger-sized cells to reduce the frequency of beam-to-beam handovers as they travel over the geographic region.